Optical interconnect technologies have been becoming essential as one type of signal I/O for computers. In such a case, it is important to achieve a required bandwidth (the number of channels) with a small size and low cost. For this purpose, an optical transceiver needs to be small in size with high integration.
In the case where an optical transceiver has a configuration including four units, that is, a light-emitting device such as a laser diode (LD), a driving circuit for the LD, a light-receiving device such as a photodiode (PD), and an amplifying circuit for the PD, the simplest use of the optical transceiver can be achieved when the light-emitting device and the light-receiving device are arranged one-dimensionally. In addition, with this one-dimensional arrangement, electrical connection of the driving circuit and the amplifying circuit can be achieved easily. However, in the case of conventional optical transceivers, in a light-emitting device and a light-receiving device, a connection point of an electrical signal and an optical signal is present on the same face, and the connection points need to be spatially separated between the devices. Therefore, it has been difficult to increase the one-dimensional linear density of the devices. Meanwhile, when a driving circuit and an amplifying circuit are arranged to be elongated circuits which are modularized for each channel, the most effective signal input and output can be achieved. Under such circumstances, in order to increase the number of channels of an optical transceiver, it is required for the optical transceiver to be configured such that a plurality of light-emitting devices, a plurality of driving circuits for the light-emitting devices, a plurality of light-receiving devices, and a plurality of amplifying circuits for the light-receiving devices which are modularized and have a plurality of channels are mounted.